排序方式: 共有65条查询结果,搜索用时 15 毫秒
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TiH合金电极是一种含氢量非常高的金属材料,用它作真空弧离子源的电极,可在真空环境下产生强度非常高的氢离子流。相比纯金属材料电极,TiH电极除了出现真空弧放电特有的融蚀现象外,还存在气体释放过程,所以它的表面形貌具有一定的独特性。利用扫描电子显微镜观察了单次放电和多次放电后阴极表面形貌,发现阴极斑在阴极表面微裂纹附近连续分布,气体释放生成很多小孔,使阴极斑区域呈絮状结构;弧流越大,阴极斑数量越多;多次放电后,阴极斑朝含氢量多的地方移动。该结果有助于了解含氢电极的真空弧放电过程,对该类放电的应用具有一定参考意义。 相似文献
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热阴极广泛应用真空电子器件、加速器、自由电子激光等各类束流装置,热阴极表面状态非均匀性对束流本征发射度有着显著的影响.本文推导了非均匀发射阴极的均方根本征发射度理论形式,并分析了逸出功非均匀性及其统计效应对本征发射度的影响.针对逸出功径向和一维余弦分布模型,计算了均方根发射度与逸出功非均匀性关系的理论数值解;基于有限差分法粒子仿真技术,开发了专用于阴极仿真的程序YY-PICMC,并验证了理论形式的正确性;针对逸出功二维余弦分布模型进行了理论和仿真分析,结果表明逸出功分布空间频数对均方根发射度涨落有显著影响,当空间频数趋于无限大时,发射度增长系数趋于1,即逸出功均匀阴极的情形;最后,分析了最接近真实阴极表面状态的二维逸出功随机分布模型,仿真结果表明随着空间频数增加,发射度增长系数统计方差逐渐减小,符合余弦模型结果的预期.本文建立的理论形式和仿真方法可以用于评估各类阴极表面逸出功空间非均匀性特征对束流本征发射度的影响程度. 相似文献
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Proton radiography has provided a potential development direction for advanced hydrotesting, and its image blur is a crucial point that needs to be deeply studied. In this article, numerical simulation by using the Monte Carlo code Geant4 has been implemented to investigate the entire physics mechanism of high energy proton beam travelling through the object and beamline and arriving at the image plane. This article will mainly discuss the various factors which cause the image blur, including the chromatic aberration of the imaging beamline, the insufficient modulation of an incident particle's transverse displacement and angle deviation, the longitudinal length of an object, the influence of containment vessel and otherwise. 相似文献
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强流激光离子源是最有希望为重离子聚变直线感应加速器提供离子的离子源之一。离子源内等离子体决定了离子源性能和引出品质,为了了解强流激光离子源内等离子体参数,采用发射光谱和ICCD成像的方法对该离子源中的等离子体进行了诊断。该离子源由一台四倍频的266 nm Nd:YAG激光器和Cu靶组成,激光束经过透镜聚焦后照射在Cu靶上产生等离子体,激光打靶能量密度约为108 W/cm2,持续时间15 ns。ICCD相机拍摄了激光照射后等离子体的膨胀过程,初始时刻等离子体垂直表面喷射,膨胀速度约为1 cm/s。光谱仪测量了离子发射光谱,谱线主要由Cu原子的Cu Ⅰ谱线和Cu+离子的Cu Ⅱ谱线组成。采用Boltzmann图法得到膨胀等离子体电子激发温度约为1 eV,采用Stark展宽法得到电子密度约为1016 cm-3。 相似文献
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Proton radiography is a new tool for advanced hydrotesting. This article will discuss the basic concept of proton radiography first, especially the magnetic lens system. Then a scenario of 50 GeV imaging beamline will be described in every particular, including the matching section, Zumbro lens system and imaging system. The simulation result shows that the scenario of imaging beamline performs well, and the influence of secondary particles can be neglected. 相似文献
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主要从基材性能、内层板的制造要求、微波多层板的制造特点等方面论述了PTFE基微波印制板的可制造性设计问题 相似文献
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Proton radiography is a new scatheless diagnostic tool providing a potential development direction for advanced hydrotesting.Recently a low energy proton radiography system has been developed at the Chinese Academy of Engineering Phyiscs(CAEP).This system has been designed to use an 11 MeV proton beam to radiograph thin static objects.This system consists of a proton cyclotron coupled to an imaging beamline,which is the first domestic beamline dedicated to proton radiography experiments.Via some demonstration experiments,the radiography system is confirmed to provide clear pictures with spatial resolution~100μm within 40 mm field-of-view. 相似文献
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